There are many various applications in astronomy which are using the WFC or UWFC (Ultra Wide-Field Camera)
systems. UWFC systems frequently have so called SV (Space Variant) properties. Images obtained in UWFC systems
are distorted by high order optical aberrations and objects on ultra wide-field images are very small. If we define the PSF
(Point Spread Function) of optical system then we can use some suitable methods for restoration of original image. How
to define the point spread function of LSI (Linear Space Invariant) and LSV (Linear Space Variant) systems is one of the
most challenging questions of this paper.